Index mechanism



March 1, 1960 D. FRITSCH 2,926,534

INDEX MECHANISM Filed Dec. 31, 1956 mmmlmn-mm 7. 5 r flu m D WJ KL 715/7509 [52 BY ATTORNEY United States Patent INDEX MECHANISM Daniel Fritsch, Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Application December 31, 1956, Serial No. 631,850

1 Claim. (Cl. 74-126) This invention relates to watch construction and more particularly relates to an index mechanism.

In a conventional spring driven watch a main spring transmits power through a train to an escapement which, in combination with a balance assembly, regulates the rate at which the main spring is alowed to move the time indicating elements or hands of the watch. In such watches the rate of rotation of the escape wheel is controlled by a palate and fork cooperating witha roller on a roller table carried by the staff of the balance wheel. The escape wheel is constantly in a state of tension, that is, in a state in which it is attempting to deliver power, so that the indexing function performed by the palate and fork must be positive or locking to prevent the escape of this power.

In electric watches of the type described in assignees copending applications, Serial Nos. 409,934 and 578,843,

filed February 12, 1954 and April 17, 1956, respectively, the former now Patent No. 2,888,797, the balance wheel no longer regulates the escape of power from a separate power source, such as the main spring of a conventional watch, but itself provides the driving motion which is imparted to the train and watch hands. The train is no longer under a constant tension so that a different means of transferring the oscillating motion of the balance wheel into the rotary motion of the train may be provided. The indexing mechanism no longer serves the function of providing a positive brake upon the escape of power from a separate source and consequently this also may assume different forms than have been heretofore utilized in conventional spring watches.

In Patent No. 2,888,797 there is shown one system for translating the oscillating motion of a balance wheel into step by step motion of anindex wheel. According to the present invention I have now discovered a simple and effective indexing mechanism suitable for use with the driving apparatus described in that application, and which is also useful with other index driving mechanisms wherein the index wheel does not transmit power from a separate source to the time indicating element ofthe mechanism.

I is accordingly a primary object of the present invention to provide a simple and effective indexing mechanism for indexing a wheel to which step by step motion is transferred from an oscillating member.

It is another object of the invention to provide a mechanism for imparting a step by step motion to the index wheel of a watch from the oscillatory motion of the balance staff incorporating a simple and effective index mechanism.

It is another object of the invention to provide a mechanism for imparting a step by step motion to an index wheel from the oscillatory motion of an oscillating member through the use of an index mechanism which includes a member having a spherical surface spring urged into apertures in the index wheel.

It is still another object of this invention to provide an indexing mechanism of the foregoing type which simultaneously actuates switching contacts.

These and further objects and advantages of the invention will become apparent upon reference to the following specification and claim and appended drawings wherein:

. Figure 1 is a vertical elevation, partly in section, showing an index wheel driving mechanism containing an index mechanism constructed according to the present invention;

Figure 2 is a horizontal section taken along the line 22 of Figure 1;

Figure 3 is a partial vertical section taken along the line 33 of Figure 2;

Figure 4 is a vertical section of another embodiment of an index mechanism according to the invention; and

Figure 5 is a side elevation of an index mechanism constructed according to the invention which also actuates switching contacts.

Referring to Figure 1, there is shown a balance assembly of a watch consisting of a balance wheel 10 carried by a balance staff 12 having its lower end journaled in a conventional bearing assembly containing a hole jewel 14 and cap jewel 16 mounted in pillar plate 18. A hair spring 20 is carried on hair spring collar 22 on the staff 12in the conventional manner.

Mounted upon the stall. 12 beneath balance wheel 10 is a collet 24 which carries a generally spiral drive spring 26 which terminates in a rounded end 28.

Mounted adjacent the spring 26 in suitable bearings, not shown, is a toothed index wheel 30 which is carried on a shaft 32. The index wheel 30 is provided with teeth 34 having one surface 36 which is substantially radial, and having a second and longer surface 38. The surface 3-8 is at an angle with respect to the. surface 36 which will permit the spring end 28 to engage the surface 36 on a tooth 40 without striking surface 38, on an adjacent tooth 42, as best seen in Figure 2.

Mounted on the pillar plate 18 adjacent index wheel .30 is a sleeve 44 which carries a spring arm 46. A bushing 48 is mounted over the end of spring arm 46 coaxial with sleeve 44 and carries an adjusting screw arm 50. The adjusting screw arm 50, bushing 48, spring arm 46, and sleeve 44 are all secured to the pillar plate 18 by means of a screw 52. An adjusting screw 54 screw threadedly passes through adjusting screw arm 50 and engages the upper side of the spring arm 46.

The index wheel 30 is provided with a series of apertures 56 which are equally spaced about the periphery of the wheel, with one aperture being associated with each tooth. Apertures 56 are countersunk at 56, as shown in Figure 3, to receive a ball 58. The upper surface of the ball 58 is received in an aperture 60 in the end 62 of spring arm 46. Spring arm 46 resiliently urges the ball 58 into the countersunk hole 56' with a presesure determined by the setting of the adjusting screw 54.

In operation, the end 28 of spiral spring 26 moves in a counterclockwise direction as the balance wheel oscillates, and engages the radial surface 36 of a tooth 40. As the spring 26 and balance wheel 10 continue to rotate in a counterclockwise direction, the index wheel 30 is moved through the angle B in Figure 2. The spring end 28 thereupon clears the end of the tooth 40 and the tension of spring arm 46 forces the ball 58 down into the countersunk hole '54 to move the index wheel 30 through the remaining distance C to complete the movement through angle A which is the angle of one index. The ball 58 locks the index wheel 30 in this ad vanced position while the helicoidal spring 26 continues to rotate in a counterclockwise direction. Hair spring 20 thereupon reverses the direction of the balance wheel 10, carrying the spiral spring 26 in a clockwise direction. As the spring moves in this direction, its end 28 brushes aeaasee by the long surface 38 of a tooth on the index wheel 30. No motion is imparted to the index wheel, however, inasmuch as no drive connection is established and the end 28 of spiral spring 26 is merely deflected toward the balance staff by reason of the resiliency of the spiral spring. Movement is also prevented by the index ball 58 which holds the index wheel 30.

While the index mechanism of this invention is il- ,lustrated in connection with a particular drive, it is to be understood that other type drives may be used.

According to another embodiment of my invention, a separate indexing ball 58 may be dispensed with and may be replaced by an indexing detent fastened to the spring arm. Referring to Figure 4 there is shown such an arrangement wherein a spring arm 62 has a hemisphere 64 secured thereto by means of a rivet connection 66. The hemispherical member 64 engages an index wheel 68 nesting in a bore 70 which is countersunk at 72. The operation of this embodiment of my invention is similar to that disclosed in Figures 1 through 3. Inasmuch as the hemispherical member 64 does not rotate but slides across the face of the index wheel 68, the wear is somewhat greater than that obtained with the embodiment of my invention shown in Figures 1 through 3, and for this reason, the foregoing embodiment is to be preferred.

According to a still further embodiment of my in- .vention the motion of the spring arm of the indexing mechanism may be utilized to open and close a circuit in the watch or other mechanism in which the indexing means is used. Referring to Figure there is shown an indexing arrangement similar to that of Figures 1 through 3, wherein a toothed index wheel 72 carried by a shaft 7 4 is indexed by a sphere 76 which engages a series of peripheral holes in the index wheel 72. The sphere 76 is urged downwardly into these holes by means of a spring arm 78 mounted atop a sleeve 80 carried by a pillar plate 82. A bushing 84 is mounted atop spring arm 78 and carries an adjusting screw arm 86 which has an adjusting screw 88 in its outer end. The adjusting screw arm 86, bushing 84, spring arm 78, and sleeve 80 are secured to the pillar plate 82 by means of a screw 90. Adjusting screw 88 engages spring arm 78 to determine the force with which the spring arm urges the sphere 76 into engagement with the index wheel 72.

e The spring arm 78 is provided with an extension 92 which extends beyond the index wheel 72 and which carries a contact 94 at the end thereof. Contact 94 engages a stationary contact 86 mounted on a post 98 on pillar plate 82. It will thus be seen that a circuit between contacts 94 and 96 is closed so long as the sphere 76 is in one of the peripheral holes in the index wheel 72. At

the moment that the wheel 72 is driven forward by.

means of a suitable driving mechanism, such as the spiral spring 26 in the embodiment of the invention shown in 5 contacts is thereby broken and remains broken until the sphere 76 drops into the next peripheral hole in index wheel 72. With this switching arrangement a circuit is closed during the time that the index wheel is stationary. It will be apparent that a converse arrangement may be used by mounting the contact 96 above the extension 92 of spring arm 78, thereby forming a switching arrangement which closes a circuit during the time that the index wheel. is in motion.

It will be apparent from the foregoing that according to this invention there is provided a simple and effective index means for indexing an index wheel driven in incremental steps by a drive mechanism. The arrangement is particularly well suited to use in electric watches wherein a balance wheel drives an index wheel and train. According to one embodiment of my invention there is shown an index mechanism which undergoes an extremely small degree of wear, while according to still another embodiment of my invention there is shown an index mechanism which serves also as a switching means.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claim rather than by the foregoing description, and all changes which come Within the meaning and range of equivalency of the claim are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

In an indexing mechanism for transforming oscillatory motion of a staff into step-by-step rotary motion, an index wheel mounted for rotation and having teeth formed with one radial face, a spiral spring lying substantially in a plane and secured at its iner end to said oscillating staff, said spiral spring extending through an arc in excess of the outer end of said spiral spring being free and periodically contacting the radial face of successive teeth to cause said index Wheel to turn in one direction, said spiral spring yielding to said teeth when moving in the opposite direction, said index wheel having a series of equally spaced recesses corresponding to the teeth thereof and extending in said index wheel parallel to the longitudinal axis of said index wheel, an index member having a hemispherical surface in engagement with said wheel, a leaf spring carrying said index member and resiliently forcing said index member into one of said recesses in a direction parallel to the axis of rotation of said wheel.

References Cited in the file of this patent UNITED STATES PATENTS 750,492 Schmidt Jan. 26, 1904 2,084,226 Strohm June 15, 1937 2,419,986 Brown Mar. 6, 1947 

